Radio receiving device



Sept. 28, 1943. G. G. ROBERTS 2,330,241

RADIO RECEIVING DEVICE Filed Oct. 17, 1941 2 Sheets-Sheet l W R R O R Ywh m m. w h mm M m e W Y W B N n m \P h H v u I i 4,/J-\||\ i n w N Q IN .2 [WI N |W| k w m xwiwoum NN QM v? H M? H m F 4 a *4 o i ww H I N w wm I L.

ATTORNEYS Sept. 28, 1943. G. G. ROBERTS RADIO RECEIVING DEVICE 2Sheets-Sheet 2 Filed Oct. 17, 1941 nlll Ill.

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Patented Sept. 28, 1943 A Gerald Roberts Akron, Ohi QasSig-nor'toWgONeil, Akron, Ohio Application Octoberl'l, 1941, serial-Nailin 7Claims. (omen- This invention relates to acommunication system and moreparticularly. toa radio receiving 7 device whichamay be remotelycontrolled to faciliate, or insure the reception'tof special messages. i

In the present'emergency it is oftentimes desirable, thatspecialmessages, news broadcasts, newsrofapproaching airraids, etc. bedisseminated torentire districts'with the greatest pos siblespeed. to,enable appropriate measures to be taken. Since'air raids;.etc. areusually oflocalized character, it is undesirable that messages bebroadcast 'throughzall the various radio stations to. which severalmembers of the populace may be listening. Therefore; it is'desirablethat only one-station, hereinafter designated .defense station becommissioned: to carry. such broadcasts; and .thatits announcements bereceived by all of the" receivers regardless of how they are tuned;

It .isan objectrof the presenttinvention to'provide-treceptivemeanswhich will automatically receive any important broadcasts from thedefense station. l

Itis a furtherobjectioi the present invention to provide receptivemeans, controllable by the defense station whichzautomaticallysubstitutes a special'broadcast ioraany broadcast being received,

It is a further object of the, present invention to providereceptivemeans controllablerby'the designated, defense station, toautomatically sub-:-

stitute aspecialrbroadcast forthat towhichthe receiverwas'originallytuned and after the special 1 broadcast iscompletedgtox-again'rtune, the. radio? receiver to its original station.

Other objects ,willbe; apparentfrom .the l'fol-t.

lowing descriptionsof;theinvention; as illustrated va-l andpf agiven-frequency. -Preferably; the

devicealso, has automatic disconnecting means for disconnecting thespeaker from-thev output of; the receiver in response to modulations ofa second g-ivenfrequency in-the output ofthe-sta tion to which thereceiver-is-tuned. The auxiliary I receiver, maybe used-alone orin-conjunction by the accompanying. drawings, in which like 7 parts aredesignated by like 1- numeralsv of *reference" throughout the'severalviews and" in which: Figure-1 shows in diagrammatic form-one. em:-

bodimentof the presentinvention; and

Fig 2 illustrates anotheri embodiment: of :the

present invention.

The radio receiving device of the" present: in-v vention has anauxiliary receiventunable to the 1 designated station, and preferably,fixedly. tuned thereto, a speaker adapted-tooperatezwhen connected .intothe output of 'the receiver; but normally. unconnected thereto,vautomatic connecting means for connecting the speaker to the out:

put of the receiver in responseto modulations 1' in :the output-oithedeiense station, which modulations are over a; predetermined minimum;interwith a -main radio receiver, and, if desired, both receivers may;have a common speakerewhich is normally connected-to the outputofsaidmain" receiver. a

Referring more particularly to li-ig. ,"1- of the drawings, thereceivi-ng means may have a selectively tunable main radio receiverh Aand an auxiliary receiver -B. The mainreceiver A may havethe usualinput-circuit with an'antenna-and a g-roundi. and theusual audio outputcircuit comprising wires 3 and 4,- between which a speak erS-is-usuallyconnected. 1

iAccording tothe present invention; automatic connectingmeans isprovided for connecting-the speaker S-tothe .output; of the auxiliary"receiver, B; which is preferably: fixedly tuned to the designatedcontrolling ordefense station for -the,area, andafori disconnectingitfrom the audio output of the selectively tunable receiver A." ,Theauxiliar'y. receiver- B may have the usualainput. circuit comprising-agroundfi; and awire 5, which iscon-i nected to. the antenna I,- and theusual audio out-:-

putcircuitcomprisingwires land 8.-

The connecting. means of tion' comprises circuit C1;

tothe audio frequency output land f the fixedly tunedlauxiliary receiverB. The circuit Cr; comprises a suitable band-pass filter N1 having.its-input,.c.onnected,to the output of thereceiver B. A rectifier tubeviis connec ted'between the output; of the-filter and the inputof a delaynetfrequency towhich the connecting means is responsiveandthe'delaynetwork servesas the means forv predeterminingthe minimuminterval through whichth'e connecting frequency must be maintained.toi'cause response thereto.

The band pass filter'Nri's tuned to 'a-control frequency Fir which isthe frequency chosen toefiectz'connection' with-the special broadcastand which. corresponds Lto ithe, control modulations :in 1- thepresentinvene; the disconnecting. means-comprises circuit C2. Both areconnected the radio frequency transmitted by the control station when itis desired to transmit a special broadcast, The band-pass filter maycomprise usual inductances 9, .IB and II, usual capacitors I2, i3 andI4, and a resistance suitably arranged and having the desired values topermit passage therethrough only of frequencies within the desirednarrow range. The input side l8 of the band-pass filter N1 is connectedto the wire 7, which is the positive side of the output of the receiverB. The output side l9 of the band-pass filter N1 is connected to theplate l6 of the rectifier tube V1. The cathode I! of the rectifier tubeV1 is connected to the input side of the delay network D1, whichcomprises the high resistance 20, the resistance 2| and the capacitors22 and 23, respectively. The output side 24 of the delay network D1 isconnected to the grid of the vacuum tube T1. T1 is suitably biased inthe usual manner by selecting appropriate values for the resistances 25and 25, which are disposed between the ground 2'! and the wire 29. whichis connec ed to a suitable source of positive voltage. The actuatingcoil of the relay R1 is connected in series with the wire 29 and theplate of the vacuum tube T1. The disconnecting means includes thecircuit 02 and is adapted to respond to a'second given frequency F2.with which the output of the transmitter to which the receiver B isfixedly tuned is modulated when it is desired to disconnect the speakerS from the auxiliary receiver and to reconnect it to the main receiver.The circuit C2 comprises a band-pass filter N2, which passes frequencyF2 but not F1. a rectifier tube V2. a delay network D2 and a relay R2.which is actuated by the vacuum tube T2. The elements of the circuit C2are connected similarly to the elements of the circuit 01. The valves ofthe inductances and capacitances in the band-pass filter N2 are,however, so chosen that they respond to a frequency F2, which differsfrom the frequency F1.

One contact 32 of the relay R1 is connected to one side 33 of the powersupply P, which may be the usual 110-volt light supply; the otherterminal or armature 34 of the normally open relay R1 is connectedthrough a wire 35 to a pole 36 of the relay R3 and to a terminal of theactuating coil 28. The other terminal of the actuating coil 28 isconnected throu h the armature 31 of the normally closed relay R2 to theother side 38 of the power supply P. A contact 40 of the relay R3 isconnected throu h the wire to the wire 33, so that when the coil R3 isonce energized by operation of the relay R1. energization of the coil R3will be maintained after connection is broken between contacts 32 andthe armature 34. Means such as an armature 42 connected to one side ofthe power line P and actuated by the relay'Rs may he provided inconjunction with the contact 45 to operate the signal device or buzzer43 when the relay R3 is first energized. In such a case. a manuallyoperated switch 46 may be provided to disconnect the signal or buzzerduring the special broadcast. The third pole or armature of the relay R3is connected to the actuating coil of the speaker S. The contact 48 withwhich the armature or pole 41 makes electrical connection when the relaycoil 28 is not energized is connected-to the positive side 3 of.

the audio output of the selectively tunable main receiver A. The contactis adapted to make electrical connection with the armature 41 when thecoil 28 is energized. It is connected to the The cathode of the vacuumtube 1 positive side of the output of the auxiliary, and preferablyfixedly tunable, receiver B.

In the operation of the device of the present invention, the auxiliaryfixedly tuned receiver B is operated continuously and is continuouslytuned to the designated control station. Normally, however, its audiooutput is not connected to the speaker S. When a special broadcast is tobe heard, thecontrol broadcasting station modulates its usual frequencytowhich the auxiliary receiver B is fixedly tuned with the connectingfrequency F1. This frequency is amplified and applied between the wires1 and 8 in amplified form. The band-pass filter N1, being tuned to thisfrequency, permits it to pass, so that it is applied to the plate H) ofthe tube V1, and if the frequency F1 is continued for the minimuminterval, it thereby causes a current of sufiicient magnitude to flowthrough the delay network D1 to provide the capacitor 23 and the grid ofthe tube Tr-with sufficient potential to cause the current to flowbetween the plate and the cathode of the tube T1. This current flowingthrough the actuating coil of the relay R1 causes a circuit to beestablished between the one side 33 of the power supply P successivelybetween contacts 34, along the wire 35, through the actuating coil 28 ofthe relay R3 and through the armature 37 of the relay R2 to the otherside 38 of the power supply. The relay R3 is thereby actuated, thuscausing contact to be made between points 36 and 40, and therebysustaining the current through the actuating coil 28. The actuation ofrelay R3 also causesthe signal device 43 to be connected across thepower line P, and the speaker S to be disconnected from the contact 48and the output of the receiver A and to be connected to the contact 49.in the output I of the receiver 13. The connecting frequency F1 istransmitted by the control station for only a very short period and whenit is discontinued the coil 30 of the relay R1 is de-energized, allowingthe armature 34 to return to its original position. The relay R3,however, is energized by current flowing between the armature 36 and thecontact 40. 1

After-the special broadcast has been received, the designated controlstation will modulate its usual frequency with a suitable disconnectfrequency This frequency will pass through the band-pass filter N2 butwill not pass through band-pass filter N1. This frequency causes currentto now between the cathode and plate of the tube T2, causing theenergizing coil of the relay R2 to be energized and causing the armature31 of this normally closed relay to be operated so as to' disconnect therelay R: from the wire 38 of the power supply, thus causingde-energization of the actuating coil 28 and causing the speaker S inthe armature 41 to be again connected to the output of the receiver A.Cessation of the' transmission of the frequency F2 automaticallydeenergizes the actuating coil of the relay R2 so that the connection isagain made between the actuating coil 28 and the wire 38. Since,however, the contact between armature 36 and contact 40 has been broken,the relay R3 is not actuated.

In the modification of Fig. 2, the audio outputs 3 and 4 of the receiverA are permanently connected to the speaker S and automatic connectingand disconnecting means are provided for suitably connecting the audiofrequency amplifier together with the speaker to the outputs of theauxiliary receiver B in response to a predetermined signal of thecontrolstation. The

aaso aazr automatic connecting :means. comprises the same elements shownin: the modification: of i Fig: 1', and is responsive to apredetermined: minimum interval. of; given modulations of the: outputsofthe station to which. said receiver: B- is fixedly tuned. Tliehroadcast.receiven'A'. may: comprise the-usual .radiozirequ'encyand'i'det'ectorportion: 5

. trol' station. Theoutput wire' 2 of the radio frequency portionoffthetreceiverAis connected tothe. contact: 48 0f the relay =Ri.'- Thearmature 41 instead of -being connected to the speaker. 53;.

as in Fig, l, is'connectedto the': input of: the audio frequency portionof=the receiver A. The short circuiting means comprises an additionalswitch orarmature 59 added tothe relay Re and operated-by the coi128.The armature Ellis connected through the wire 55 to one teimin'al-of theon and-cit switch 51.: The. contact tilt is connected to the otherterminal" of -the switch 51 so. that when-the coil ZB of 'the relayF'nis energized, current flows between thearmat-ure 59- and the contactfiil to short-cii cuit the switch 51, so that power is supplied to thereceiver Ax Inthe operation of the modification showndn Fig. 2, thepredetermined connecting signal-received'by-the auxiliary-receiver Bpasses through the circuit C1, as above set forth, and causes the relayR3 to close, which disconnects the input 54 of the audio frequencyportion from the detector output 52 and connects it to the output 8 ofthe auxiliary receiver B. Simultaneously, the switch 51 isshort-circuited by connection made between the armature 59 and thecontact 60 of the relay R3, so that power is supplied to the audiofrequency portion of the receiver A. This portion, together with thespeaker S, is thus automatically connected to the output 8 so thatsignals from the auxiliary receiver B aresubstantially amplifiod.

When disconnect frequency is received by the receiver B. it passesthrough the circuit C2. causingithe coil 28 to be de-energized and thedetector output 52 to be again connected to the input 54. If .the switch5! is open, the receiver A is disconnected from the source of power.

The modification shown in Fig. 2 is especially desirable in that theweak signals from the auxiliary receiver B are considerably amplified.

The control portion and connecting means of the invention'disclosedherein is claimed in my application Serial No. 456.630, filed August 29,1942, which is a continuation-impart of this application.

It is to be understood that the particular form of apparatus shown anddescribed are presented for purposes of explanation and illustration andthat various modifications of said apparatus can be made withoutdeparting from my invention as defined in the appended claims.

What I claim is:

l. A radio receiving device comprising an auxiliary receiver turnable tosignal energy from a transmitting 'statiomiraispeaker:adapted to operat'e'when connecteddnto' the output of. said receiver; but normallyunconnected: thereto; con; necting? means; including. a: rand-passfilter, a delay network and-a relay which are connected in series to theoutput of said-receiver, said filter beingl'capable of transmitting onlya lirnit'ed fre quency rangeand beingadapted-tooperatesaid relay bycurrent passed therethro'ugh, for connecting said speaker t'osaid-receiver in response to a predetermined minimum interval ofmo'dulationsof the output of the station to which said receiveris tuned,which-modulationsare within said: limited frequency range; a signaldevice;- a -power supply for "saidsi'gnaldevice; and me'ans alsooperable by 'afrequency within said 'limited range m operativelyconnecting said signal device-to s'aid power supply;

2. A radio receiving device comprising an'auxiliary"receiver-tunable toa signal transmitted fronra transmitting station; a speaker adapted tooperatewhen connected into the output' of said receiver, but normallyunconnected thereto; and connecting means including arelay, which isconnected to receivecurrent from a bandpass filter connected I to theoutput-' of said receiver; for operatively connecting said speaker tothe output of said'receiver inresponse to a predeter minedminimuminterval of" given frequency modulations 'in the output of thetransmitting station to which said receiver may be tuned; means formaintaining operative" connection be- I tween said speaker and saidoutput regardless ofwhether or not said modulations are continned;- andautomatic disconnecting means 'for disconnecting said; speaker fromtheoutput or saidreceiver in A. response to a predetermined minimuminterval 'ofm'o'dulationsof said station having-a second? givenfrequency. it

3; Hradio receiving device comprising anaux iliary receiver tunable to asignal transmitted from a transmitting station; a speaker adapted tooperate when connected into the output of said receiver, but normallyunconnected thereto; and connecting means including a relay which isconnected to receive current passed through a band-pass filter connectedto the, output of said receiver, for operatively connecting said speakerto the output of said receiver in response to a predetermined minimuminterval of given frequency modulations in the output of thetransmitting station to which said receiver may be tuned, means formaintaining operative connection between said speaker and said outputregardless of whether or not said modulations are continued, andautomatic disconnecting means including a relay and a band-pass filterconnected to the output of said receiver for disconnecting said speakerfrom the output of said receiver in response to a predetermined minimuminterval of modulations of a second given fre-' quency in the output ofsaid station.

4. A radio receiving device comprising an auxiliary receiver tunable toa signal transmitted from a transmitting station; a speaker adapted tooperate when connected into the output of said. receiver but normallyunconnected thereto; and

tion to which said receiver is tuned, for oper- Y atively connectingsaid speaker into the output of said receiver; means for maintainingoperative connection between said speaker and said output regardless ofwhether or not said modulations are continued, and disconnecting meanscontrollable by separate given modulations in the output of thetransmitting station to which said receiver is tuned.

5. A radio receiving device comprising anauxiliary receiver tunable to asignal transmitted froma transmitting station; a speaker adapted tooperate when connected into the output of said receiver but normallyunconnected thereto; and connecting means including a relay which isconnected through a band-pass filter connected to the output of saidreceiver for operatively connecting said speaker to the output of saidreceiver in response to a predetermined minimum interval of givenmodulations in the output of the transmitting station to which saidreceiver may be tuned, said connecting means including a, delay networkfor predetermining the minimum interval of modulations to which saidrelay is responsive; and automatic disconnecting means including anotherrelay which is connected through another band-pass filter to the outputof said receiver, for disconnecting said speaker from the output of saidreceiver in response to a predetermined minimum interval of modulationsof a second given frequency in the output of said station, saiddisconnecting means also having in series with its relay and its filtera delay network for determining the minimum interval for response tosaid second frequency.

6. A radio receiving device comprising a selectively tunable receiver;an auxiliary fixedly tuned receiver; a speaker normally connected in theoutput of said selectively tunable receiver, but adapted to operate inthe output of each receiver; connecting means, including a band-passfilter, a delay network and a relay connected in series to the output ofsaid fixedly tuned receiver, which band-pass filter is capable ofpassing a given limited frequency range, for connecting said speakerinto the output of'said fixedly tuned receiver when modulations withinsaid given frequency range are transmitted by the station to which saidauxiliary receiver is fixedly tuned; and disconnecting means, alsoincluding a relay, a delay network and a band-pass filter which isadapted to pass a second given frequency, for disconnecting said speakerfrom the output of said selectively tunable receiver in response tomodulations corresponding to said second given frequency transmitted bythe station to which said auxiliary receiver is tuned.

7. A radio receiving device comprising a selectively tunable receiver;an auxiliary fixedly tuned receiver; a speaker normally connected in theoutput of said selectively tunable receiver, but adapted to operate inthe output of each receiver; connecting means, including a band-passfilter, a delay network and a relay connected in series to the output ofsaid fixedly tuned receiver, which band-pass filter is capable ofpassing a given limited frequency range, for connecting said speakerinto the output of said fixedly tuned receiver when modulations withinsaid given frequency range are transmitted by the station to which saidauxiliary receiver is fixedly tuned; a signal device; a power supply forsaid signal device and disconnecting means, also including a band-passfilter which is adapted to pass a second given frequency, for.disconnecting said speaker from the output of said selectively tunablereceiver in response to modulations corresponding to said second givenfrequency transmitted by the station to which said auxiliary receiver istuned, said connecting means also including means for connecting saidsignal device to said power supply therefor.

GERALD G. ROBERTS.

